Search results for "plasmon"
showing 10 items of 614 documents
Pulse nonlinear optical switching in plasmonic structures
2020
We study switching operation in a plasmonic coupler using fs-pulses. Simulations using the finite difference time-domain method (FDTD) are carried out showing how the output changes as the pulse energy increases raising from zero to a maximum. Both cases of neglecting and realistic losses are considered in order to compare. The work is intended to explore the use of pulses for all-optical signal processing in a potentially interesting system for integrated photonics at the nanometric scale.
Scaling the Sensitivity of Integrated Plasmo-Photonic Interferometric Sensors
2019
We present a new optical biosensing integration approach with multifunctional capabilities using plasmonic and photonic components on the same chip and a new methodology to design interferometric b...
Photoemission Electron Microscopy as a tool for the investigation of optical near fields
2005
Photoemission electron microscopy was used to image the electrons photoemitted from specially tailored Ag nanoparticles deposited on a Si substrate (with its native oxide SiO$_{x}$). Photoemission was induced by illumination with a Hg UV-lamp (photon energy cutoff $\hbar\omega_{UV}=5.0$ eV, wavelength $\lambda_{UV}=250$ nm) and with a Ti:Sapphire femtosecond laser ($\hbar\omega_{l}=3.1$ eV, $\lambda_{l}=400$ nm, pulse width below 200 fs), respectively. While homogeneous photoelectron emission from the metal is observed upon illumination at energies above the silver plasmon frequency, at lower photon energies the emission is localized at tips of the structure. This is interpreted as a signat…
Femtosecond time-resolved photoemission electron microscopy operated at sample illumination from the rear side
2019
We present an advanced experimental setup for time-resolved photoemission electron microscopy (PEEM) with sub-20 fs resolution, which allows for normal incidence and highly local sample excitation with ultrashort laser pulses. The scheme makes use of a sample rear side illumination geometry that enables us to confine the sample illumination spot to a diameter as small as 6 μm. We demonstrate an operation mode in which the spatiotemporal dynamics following a highly local excitation of the sample is globally probed with a laser pulse illuminating the sample from the front side. Furthermore, we show that the scheme can also be operated in a time-resolved normal incidence two-photon PEEM mode w…
Narrowing the Plasmonic Sensitivity Distribution by Considering the Individual Size of Gold Nanorods
2018
The plasmonic nanoparticle sensitivity, sensing volume, and the signal-to-noise ratio are strongly dependent on the nanoparticle dimensions. It is difficult to chemically produce or purify nanoparticles with a size variation of less than 10%. This size variation induces a systematic error in sensing experiments that can be reduced when the exact size of each individual nanoparticle is known. In this work, we show how the size of gold nanorods can be estimated directly from the optical spectra of single nanoparticles by using the increase of radiation damping with the nanoparticle size. We verify our approach by comparing these spectrally estimated sizes with the precise sizes of exactly the…
Probing large area surface plasmon interference in thin metal films using photon scanning tunneling microscopy.
2003
Abstract The interference of surface plasmons can provide important information regarding the surface features of the hosting thin metal film. We present an investigation of the interference of optically excited surface plasmons in the Kretschmann configuration in the visible spectrum. Large area surface plasmon interference regions are generated at several wavelengths and imaged with the photon scanning tunneling microscope. Furthermore, we discuss the non-retarded dispersion relations for the surface plasmons in the probe–metal system modeled as confocal hyperboloids of revolution in the spheroidal coordinate systems.
Surface plasmon polariton propagation length: A direct comparison using photon scanning tunneling microscopy and attenuated total reflection
2001
The propagation of surface plasmon polaritons (SPP's) is studied using a photon scanning tunneling microscope (PSTM) and conventional attenuated total reflection (ATR). The PSTM experiment uses localized (focused beam) launching of SPP's at a wavelength of 632.8 nm. Propagation of the SPP is observed as an exponentially decaying tail beyond the launch site and the $1/e$ propagation length is measured directly for a series of Ag films of different thicknesses. The ATR measurements are used to characterize the thin film optical and thickness parameters, revealing, notably, the presence of a contaminating adlayer of ${\mathrm{Ag}}_{2}\mathrm{S}$ of typical dielectric function, $8.7+i2.7,$ and …
Surface plasmon polaritons in metal stripes and wires
2004
Surface plasmon polaritons (SPPs) are collective electron oscillations coupled to a light field which are propagating along the interface of a metal and a dielectric. As a surface wave, SPP modes feature properties essentially different from light-field modes in all dielectric structures. These properties could allow the realization of novel photonic devices that overcome certain limitations of conventional devices. Specifically, the realization of two-dimensional optics and light-field transport in sub-wavelength SPP waveguides seems feasible. In this review we discuss recent experimental advances regarding SPP waveguides, i.e. laterally confined metal thin films that guide SPPs. Electron-…
Single-Crystal vs Polycrystalline Gold: A Non-linear-Optics Analysis
2017
Standard gold in the field of plasmonics is obtained by evaporation or sputtering and therefore is polycrystalline. Yet, this gold presents numbers of drawbacks such as roughness, grains and ill-defined electronic band diagrams in addition to the lack of reproducibility from one instrument to another. It is, thus, beneficial to turn to a metal production that can enable well-defined and controlled gold parameters. To that end, we have explored the wet synthesis of gold nanoplates which represents a simple and robust means of obtaining single-crystal gold (Guo Z, Zhang Y, DuanMu Y, Xu L, Xie S, Gu N, Colloids Surf A 278:33–38, 2006). The synthesized nanoplates are from 50 to less than 100 nm…